The decision today by Tennessee Sen. Lamar Alexander to cut short his role in the Senate GOP leadership boosts Texas Sen. John Cornyn in the San Antonio resident’s behind-the-scenes campaign to move up to the second most powerful post in the Republican leadership.

Sen. John Cornyn (Official photo)

Alexander’s departure from the Senate GOP leadership averts a looming showdown with Cornyn in their contest to become Senate GOP whip in January 2013.

Alexander told Senate Republican colleagues in a letter today that he was giving up his post as chairman of the Republican Conference – the third ranking post in the Senate GOP leadership – in order to return to the GOP rank and file.

Alexander said he wants to try to build bipartisan consensus within the Senate rather than continuing to serve as a partisan voice for the Senate GOP leadership as he heads into his 2014 re-election campaign back in Tennessee.

“Stepping down from leadership will liberate me to spend more time working for results on the issues I care about,” Alexander told colleagues in his letter.

Alexander’s departure from the leadership in January 2012 ends the potential struggle with Cornyn to succeed retiring Sen. Jon Kyl, R-Arizona, the Senate GOP whip.

Cornyn, currently leading Senate Republicans’ campaign operation, announced last February that he would seek the post of Senate Republican whip when Kyl leaves the Senate in January 2013.

With Alexander’s departure from the Senate leadership. Cornyn could have an uncontested road to the post as deputy to Senate Minority Leader Mitch McConnell, R-Ky.

“Senator Alexander is not only an exceptionally effective leader in the Senate, over the years we have become good friends,” Cornyn said in a statement.

“He has done an outstanding job as chairman of our conference and we have all benefited from his wisdom and guidance. I am pleased to hear that Senator Alexander will run for re-election in 2014 and I look forward to serving with him for many years to come.”